SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51cdd118a800d8c5d0b70dfebf4037cc30167766939d6d82ff422978bbba6602' 
  AND token = '+n3BvHThDCtQYTPI+GZd1eb5iIoJYtL38PB0JX7FVEw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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