SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14d323475390fd267e3d9062dec9619b1829daacff494fb0ec8a73e6bf1a19ce' 
  AND token = 'JMusMwB49NotRbQ4aRMp8imbJVEIlCs+f0QDyB9YQUs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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