SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8a7a6d1b5374282ff192efed02d0fabae896aefe715328563fd69abbd59226b' 
  AND token = 'tI6UVArFN6uGPgbz2/rt2BgESbZwIq60OMJVo7TDjZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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