SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a2378bae6b5a92fa4831101c10109cdc69120db218795f143d3e515d3671dec' 
  AND token = 'P9FkZhHz0RYkmA49IJGe4UiE39LKNKQKCKNGr0ywwQM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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