SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ee43d838631b0c1e76e7fe4fd7defd87ddfc7b66294994a27f7fa4560898886' 
  AND token = 'q5bH3MKF4StGNmeZRSHXzXbaA7tyc9tOndmsatFmuPU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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