SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '392b25af12bae2a55d294e0be2a6823104ed40b8cc54b6995a58b545f6bb1358' 
  AND token = '4F4N5lCqFnGhs9/JCTcfYR4ulZhVtgF+wwTKplFgfX8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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