SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9f15c5a353269014bc885ff9b46168fefd59a2af3d7f346fd155f41c6e1e51f' 
  AND token = 'Pb6EwH0PliDjHxehrn7ZKIoPeZzqnANGuGZzaDXY+8c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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