SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '6fec1610b7fccd4824eac16c9bcbc3daf06cf4602f42814b76a56308001fed81' 
  AND token = '5tB0+iZn8wnRp/khWAqYezyFuoCm4m+ew6uGhAvGK0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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