SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6ec68da578ab43b1907f4ec62da8e3a5b0832c86f287e187d70595b8bdde24a' 
  AND token = '+gKu4nhpKB9cKOqR8sIaYm9bzf6NJ6OMsAlUwFzdPXU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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