SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f135978399997ccf9df108cc6b1dbe5f6c83eb43c8b026289f08e9a7196f5e8d' 
  AND token = 'hB0wLvn0PuQCgAu45ZIum/+dtXrL3wjOqi+R5g5JBdw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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