SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8eb6d2007fd81a609618db4f33168e48806255660c0c2d4d008f60950423ae1' 
  AND token = 'gxwzpNbKQ1jYqGs2UB848w+uKQhJ1uTSzQHbTIEU4xI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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