SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37f7720443e2fca6605400150f87ffeeb45c52509a8be44087eadccafd4fee12' 
  AND token = 'gbAdP8i0A3savRFKiXTLzewosOPlnCqZEIe2OYWBhO4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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