SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68f84be1c7b3189a43f331b0475e28e5d0769f9aed22d54cad13bd3287ac6fe4' 
  AND token = 'D5kbf0uoMCkfScY7/C3sE2O1Xeo+X/Io3gZbK/F6kP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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