SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a183258cf287e9a67bbde361afa3fb5638a9678392e1843ea331593b2d8a8f3' 
  AND token = 'cfUFIeBuvIfieTQg1SOHhIs5hLtz91RNk01YMNuFdjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}