SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af6eea707274877e8fb81eecb1f6e7204c679a1b499060d0b6cce96056547a91' 
  AND token = 'l/agxF3y8SCeJIdBdHrY1f2J9Y0PebOXjXFWe5Vk/Ec=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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