SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38875a780fa17472946e7d442d69da302683427e105e4fb29c6c41d8fe09722a' 
  AND token = '9EgqIMDKHRZ51z8LvCnzvfw4y4LWzL6GjgJwzvBvR5E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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