SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8fbb28a0c5dfd03b489c9b09e4dc7468346d4efb189f5f90610f95619635e12' 
  AND token = 'UAtaGKzUSpY0PnJEKbpt3bSdXtgxrHWsxX4No6MyL2E=' 
  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"
    }
  }
}