SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3404f731c744102089e8497f725ae89590131402f0811f350e317bcbda7ba9d' 
  AND token = 'g7VbGvFUcPlAvad53JEfJKkFbRdiPzh9zgyEMZjqz+M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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