SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a198b568852c74364ba02f0a6136a32b439d3d7b13f904cd08e190f6c327d24' 
  AND token = 'zYhnnn2CWUnfPET3iZIYFWk1ISfanjZ2SL+daUfMVXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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