SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4127e1509b398806926865737d21f9fb4e910d05bcf45ed2e461baf27d97375b' 
  AND token = 'ONpwFKoF3AJsSDhYSt3WRZ2GYQxMLQP9SqceQRi+UxA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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