SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '543a397666f26383d6c8d81e51285f9a8a4c29774799417bfbaafc61514e07cd' 
  AND token = '/DnQCN8fMCngrNKQZbUbQgAWNdx0cNR6PNNaKEt2eQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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