SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '50a501daeb9eef23d18c547f22a748efdc79e6a71efa73942842808477c3a952' 
  AND token = '8Q8RiuwyTEnX1ejoWrKisNah0+ZM4ei/DfOwF46S2xs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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