SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a68a6b5bfa163d257af757b204b8db31eb8ba2f4028c71e9a2aeb80bdd7ea59c' 
  AND token = 'v8e8jrW3Wk/YptKapTxTkqzsZyG4L94h/gyQDn+cuQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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