SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '890820190d85a3139b87a322c7312237f8a540085b69997a9c608fb2e7bbabc3' 
  AND token = '8XqQas8IlJpHqc5ZiCUaqBXEEEuXFLbSYmQLJe84qrA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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