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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'acb4acba453fc5aaf935b3f7f65e68a43fd1ee1358f66c7be10d590c190cc347' 
  AND token = 'yLmLc9VeqcBMTp+PyMuICpUcKiW3Q6tKvD7jyb7+k2k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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