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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '752ce69e3441cc2fc4cd2b8298aca7a9aa2f2107f350644e1840431cb87f5271' 
  AND token = 'sUuB/VKPkfNv69cePQtcSuVtMRBke0Ay/y1E/SHZakg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}