SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b8bb271ce5f82cfece256b0642f1fafe6c70a5d1eb44d51b22972d1fb19d314' 
  AND token = 'XLFHCwhadMAJ6wW0brFhiHUDuBtruIyePHMQXZRmMNQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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