SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6e9531ecc2ea22ea2ab58d947da445b5762a9dcf70591a1a883dc4edad34579' 
  AND token = 'A3n8tfb/WCSN2ZdBkw4g552XoEU2CxPJV7kspmgH84A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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