SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e8f7aa289511db1a3f74eb7dff1ac6a63654aeb6b3045d0080307534096a373' 
  AND token = 'DqJjttEkZZMnyCkTV9PfB62vTvBUYdyR8ps/BjYk3hw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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