SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '380d11856824082ce0ce270300b4f60a38fc30441c5830e1f9f7826819147dbf' 
  AND token = 'UReB3MJ/cH/gwZ2sDAnd4AIJgnLYDHyZGt6iqUsmg64=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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