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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e5f85646666e3578f33bac39ef68fb6f486e6d986cd977edc14aecfb986e6c0' 
  AND token = '/w4CHuzGbjE4c4EWh9SSQVf9Ar+xqIoaPcOOTT05QPs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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