SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe3e994a1743d80063c3c1c6af331b1d85c9a8bb9e4ad54e74f83d53b1e96348' 
  AND token = 'M6O0umCAnLg/a/oYpkW/ke0+oBMe/fi3Tpjkylbti+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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