SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '5a4441b781d2113e2e28196844adf05467675a4a3b0fd56f7d802de193da8351' 
  AND token = 'vUqcsmi/nSyVALUAcb/PAVW/whtsa1lnGqSSwJR7+Yo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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