SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81e0732f4269432755195d3296a64bcbae6dbcb43a6defe9e18994014efa2148' 
  AND token = 'xSdgnn890CEgfIF37cTfftDNCoeL5NDkuJsQnXgrYuo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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