SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7dcce31704b36f22705be649a348e02a67f03556fd18cb991e71d8337555204b' 
  AND token = 'mvHt1CZ7u3vMWvAUZcmYDvHMfT6gi/iqw/Owf0EKBxU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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