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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6887b8510382a1437844c16e1a1a168ef5fac6b2e33bfc0a9a9d53b1421843a' 
  AND token = 'EG1D/LTXtAFqvCENz4eaHV0eoSlZRntvkwlPvXe8t4Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}