SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c0e340ace06ce6b60f4b35f9fa37d5854f0f9309045e17d7af092e26c083569' 
  AND token = 'oEzCSXkQJlW5Fx/2ALR2WSVQKBzyRvds0JSeOX+suxw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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