SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '353293db50e1c702850a6f37b4aabb79ec830c103da5f7dbd405ea07a3b76f2a' 
  AND token = 'DJyoWB/81Ofs2hytYIMSlRdDqJhocUpoBevsSeLHHDU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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