SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd7b52e72c7a55ab96ec076ba8ee4750473295d33352c10a1a85f04912cf299c3' 
  AND token = 'aN0e+PjdC3MZpRWovZaU/aH5XQyDLxWne9VrInOiqko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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