SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9526ab1f0948706ef19711c41cf5538ba71f90e1e0a2851d1d29c58431b937a' 
  AND token = 'o3lDEFZpBsv39kniGG4eYKJ5S+0jhH/nxpLa8hyifAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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