SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef93a36ef228975ecad1f269b726791455e9a33dcd824df1ab53699c1a0c46af' 
  AND token = 'XL8S4RHbY+XgKRUvmOxjOe8w9E4amT+pVTsTrk6QmGw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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