SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '647fd6b9fe77bd1224824f449f6dda4c0dc19755d73be8ab42327be80349363c' 
  AND token = '+UMHMNXTfHOW1FMbwygJiYUD6Syl+aHgwRQzr9gAUJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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