SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '705fd967fb5bec061c3db0e61288aea461070578b74121043c7432acf88fb3f3' 
  AND token = '5MKAvqNFZ7Q/JGFs00iBr75n4/Jx5UGK0zXKOHygFx8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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