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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c893886c920f7a44ed99b11283f6c9094db4dfb16a5ac30e6b172308a6a58e18' 
  AND token = 'lCo6datQaFa/sPHZ3m4a0j1eOyjktCyFDTqm6f9KowQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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