SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc818ab7569dc53000f7d688ff53df20d899c56b6de7866e5c4e499b73753621' 
  AND token = 'HGRe7t3uthTEvZ6kqUQmZSsqKgezi9sXkpPJuCIx/zA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}