SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1c7fc98d783e686b1cfe165ff34884e2aed2c04f17bcfc14aab5243cbf6f788' 
  AND token = 'A/2OBcwfiwChtxfm+YFW9bTjqxlMRxk0120RygzcNYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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