SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ab5391a4c9365c424c2d58350cf92d95d407aa56772f7386f895111828c0621' 
  AND token = '+T0ozVAGAgqm/433jSGZJH+HpOotRagoW6DpTJL1SHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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