SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4499231fb4633a5c8ca5111ac9b6cef75aa5a50d2a1d8f916c591ad5db444ca4' 
  AND token = 'nfbYbJtFbLjYlABfSQ3DgiDubvsJ3ursxmuxAV/NiHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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