SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a11cd1dc8e18189490f43cb1aa8bc6c58e11cac2ae4745e9890cbfc9bdc1658' 
  AND token = 'BvPRqzp62IuwgiyBbvxS/Dw3IbmZO84sFPmfo/eih8k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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