SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90e95b4c2c1bac3931febde719c9092bf737ea754ff0482b4eaa0551ade69a31' 
  AND token = 'LJSdFwMhAB7d5nvGsCwS72OZrnX1toFhEJrA99ezES8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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