SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb912583194478aa6d02802d49ec21c6f92a7e440c52afa810161c9ce28d971b' 
  AND token = 'QFsXLE3Zi2qK5a+HiJyMKrVMIWpHTaBgCwsKUzURvTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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