SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1cdf055059a100ef12eb565d74a8f00607b93c7e681090172243e6f27d7cfdde' 
  AND token = '6FiBBgJdRHbIWMI/lUxUzjhnFvIsgZ2oUlQt0Y6G4zM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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