SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ffb3b68c57c30b4fa8324ad8bfd9bc9ae84f53b47ddc0a40041d0aa204644a4' 
  AND token = 'TIucXiINLEtBI0x/+3XNvkAzkK8a0TLEOacCMNDwjVU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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