SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f592a6834aa28ff7dec1351c4beeeaf0ec10698df4d0e62eec2b06bc702364ae' 
  AND token = 'Kq+1Sk8CwOzyM6RQZ8+46tFxCw3s6qSeE3sUTggWaaY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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