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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81fbc980166e2bfbc3886ecb5881cfc70b8b80a41b2ff361d75611b0d619ed9c' 
  AND token = 'UNdk8E8nxtqMGyk5xFkSl31iu8NydUf7weImkeXSoNQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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