SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f51dbe4a6cf8db5b266cbe70e1de4d69fadc997049e38564484f3d2c188fd3d' 
  AND token = 'sMJw9HrYJlR2dVvLqZ3FGUoueGckNppcB/0XZ+JDHjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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