SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2a643e8e1539448d1b21bcefa52f81b68542fa668a162a4a958c9053703f3c6' 
  AND token = 'KhE5YMuM24g3Nlmb2dBsTkd24lcmcwaxfJc8JiItuJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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