SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ade253a7cb8812ac486e8bf0ee0e03ccb2e4879139dd238e5412e87a00cdadba' 
  AND token = 'FgjDHtRxfpqJCVkRlv90gS7Qsa1jVRovBzzpQxYCQ3A=' 
  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"
    }
  }
}