SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4b877c4ef68bdfbc116fc550182d1889120213066a284f93b6c2873e8d0735e' 
  AND token = 'vFOOLj54CpvZrgbhBeS+uOdDLHI7sgoT8vf8NezdRcc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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