SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19502d0a3ef7bbfafc42fb95c690e9d7849814b66666d687f77d29f91de715cc' 
  AND token = 'Kzo/QfsAzDaKYuWGf8QC3+e0bZ9nESFgn1BnCQV++gI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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