SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a46e785380fb5795eee688207fa840fe9ca8789eea9ca31523e37b3f553b7043' 
  AND token = 'WVE+VYcVksoff9yJreYQYHE+nnINnP1EVVWjv5SsDdA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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