SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90816a288b315e5765f5482587e04dcefe3126ce6334c949bfb5bf784c5a34a2' 
  AND token = '4Ei1DJ3OvkLEuON+zmqbiPbscIiXxwmVV0hZq1Sz5K8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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