SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '263b41a5436d78d10e2297f5c034264cf94c42e3b12ff993bbe5e791573f208d' 
  AND token = 'yOmAuZDN+Q9gCdBO0pLjldIRGm1Hu9NxHR5SlyVFBFU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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