SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c82d510b0b5faaedc430ed2db175e7df231e8f2f839e57183d3c4fdb003a6ec2' 
  AND token = 'IwWsZoGYTsE2YL0NU86Fv1ar3qL/aRtxc+Qwox5NErk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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