SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dff129984f9a710ae10510757b347e8352ee72608ebcfb084bb918e6be81c5b' 
  AND token = 'anD6JNe9Ps7NUGV39rrz7iQbfR0uyR86ZVI6vUcYJGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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