SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a505698653e3596f72321a72af32fdad6cb77953b630a7e361846f66548d5fd' 
  AND token = 'D8QobjxCG+7T3QOQQnTOYlTx9481nEj3gOyfqmeuZbE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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