SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29b928847bf7a30dc2aa5f1b1d1e95a1c90443d394d45a9eb701836454a4a499' 
  AND token = 'mSDtVpbxKJYmQps2TBlcKu/Jl7dnrlCDvow/HjcGdfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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