SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '4a096b5bb0f96e73b70269e02286712fb883836cf4e9522c203f16902d56793d' 
  AND token = 'PCoDAFWH3rG0vQMM+Cdv9aH8z/xEZVXdPlMF+GveLjk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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