SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '45182a464802281c4d58ad447fbbfd69e3b8ab75aa0018e78030414644e179d3' 
  AND token = '15N0s9LmNf+fdgdmYD9GnVTAZ8iqtlKR+y/36p03rGM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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