SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f3fa7ac3fac18af51f804630db581b04933ac0d0e1e3ac82924135e4932ea9a' 
  AND token = '0ZFzyOclXQc+wFjWLLJ1nwUUXDyf9AWV6p8W6C9hL60=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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