SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57f1dde572bd10a71c13cc21defb3b40d8c0e24106c95f97e5392cd940061e99' 
  AND token = 'fDmThiY5da8FPDyzwHz/CKRfGRKRoqPaTKXmy9XQ+Io=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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