SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4db77e3e354ba328e971e9f564518c350ce9a76250736097e80b07276262773e' 
  AND token = 'HvlAt+8uVHfvxL8M7TO3mV3gmc/5FiViZv2TbDjin4s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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