SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'abaf600840e96e64a0683f98f4970891598c2d5781258301cb071eaa8c77b0e6' 
  AND token = '0mcr23p6WjaPcor6sA2dxoyFijJy+SxmfwT/KHzJvg4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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