SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18929961ddf2003400a6e47119911beab64a25982054c67d5f305b7eac4bb61c' 
  AND token = 'T4NXDnHwGx89UH7o8cIm9St9gFZIERStb66bwcbqsKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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