SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e7f0dfe4d822582a7c121db9b620c037d3b3fd6135b1123f68004f1c3da3b85' 
  AND token = 'ZmDzVo6jpYI4zMCfJw4jh9yWdLFM9QwKy+VHoXBfXWM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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