SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '301446e3beae2a0ae9b2baed7f25943151d93b77da7c6c6610d3e334002c295c' 
  AND token = 'PCnfGHxzJFQBaWaCjr4zLB6xyA5QTKLa+4nfiXgdiwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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