SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b5700981eb4dc95688f1c5a8c46e4046496c22849e049a11398313d361c1ba0' 
  AND token = 'H9Cpc5si8YUEMRWPf2SgMwHVbB7nhvRBFEQLUlCKh48=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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