SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be38dceb1301ff4927522c7136bc2434c86afa54300f664371a2b68ed2600431' 
  AND token = 'A1lcMC/fkd6dQbhWHbEp32hb2evwFi6/207Xm9MZSHk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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