SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4938908e8ee6745a72de5a294546f507fd48d9fe6eeb62c4ca0420395096d565' 
  AND token = 'jIfUID8UYakRGSOGHJ/jnZdZqMbXf2mlVXfWzmqg54M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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