SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '175399c420e0b7fc3b8e9d9a19f31f286a382afab20502737082372330bec7c8' 
  AND token = 'd0nl2wSuYGgEZz1DU+KHOyz1pQzmaXMa+vxxBoPwk5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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